There has been known a wireless communication system including a mobile station and a base station (see, for example, Patent Literature 1, Non-Patent Literature 1 and Non-Patent Literature 2). Such a wireless communication system carries out Auto Frequency Control (AFC) that approximates the frequency of the mobile station to that of the base station.
For example, the mobile station accomplishes AFC by: receiving a signal transmitted from the base station; and correcting the frequency of a clock signal to be generated by an oscillator circuit so as to compensate for the phase difference of the received signal from a certain reference phase.
The Third Generation Partnership Project (3GPP) restricts the allowable error of the frequency of a mobile station compared to that of a base station to 0.1 ppm. The unit “ppm” is abbreviation for Parts Per Million.
Accordingly, when a carrier wave has a frequency of 2 GHz, the frequency band corresponding to 0.1 ppm is 200 Hz. When a carrier wave has a frequency of 800 MHz, the frequency band corresponding to 0.1 ppm is 80 Hz. Therefore the allowable error of the frequency of a mobile station compared to the frequency of a base station is different with a frequency band used for communication between the mobile station and the base station.
[Patent Literature 1] Japanese Laid-Open Patent Publication No. 2010-145276
[Non-Patent Literature 1] 3GPP TS 25.101 V12.3.0, “Technical Specification Group Radio Access Network; User Equipment (UE) radio transmission and reception (FDD) (Release 12)”, [online], March, 2014 [retrieved on May 14, 2014], Internet    <URL:http://www.3gpp.org/ftp/Specs/archive/25_serie s/25.101/25101-c30.zip>
[Non-Patent Literature 2] 3GPP TS 36.101 V12.1.0, “Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception (Release 12)”, [online], September, 2013 [retrieved on May 14, 2014], Internet    <URL:http://www.3gpp.org/ftp/Specs/archive/36_serie s/36.101/36101-c30.zip>